Method for the simultaneous preparation of a diolefin and an olefin

ABSTRACT

A method of preparing a diolefin and an olefin or an alkenyl benzene hydrocarbon simultaneously from more highly saturated hydrocarbons, said latter respectively having the same carbon structure as the desired end product pair, wherein the more highly saturated hydrocarbon precursors are reacted with oxygen to form respective hydroperoxides, the latter are reacted with an ethylenic hydrocarbon having the same carbon structure as the diolefin precursor to form an epoxide or glycol which are in turn dehydrated to the desired diolefin; the first hydroperoxide forms an alcohol which is dehydrated to reform the ethylenic hydrocarbon for recycling; the second hydroperoxide forms an alcohol which is dehydrated to the desired olefin or alkenylbenzene (depending upon the form of the precursor); and the ketone byproducts formed during the reaction of said hydroperoxides with said ethylenic hydrocarbon (these being the other principle byproducts in this process) are reduced to an alcohol and then dehydrated to said ethylenic hydrocarbon for recycling. The foregoing process is particularly advantageous in the simultaneous production of isoprene and isobutylene from isopentane and isobutane or of isoprene and styrene from isopentane and ethyl benzene.

United States Patent Gislon et al.

[54] METHOD FOR THE SIIVIULTANEOUS PREPARATION OF A DIOLEFIN AND AN OLEFIN [72] Inventors: Andre Gislon, Paris; Joseph-Edouard Weisang, Le Havre; Jean Maurin, Montivilliers, all of France [73] Assignee: Compagnie Francaise de Raffinage, Paris,

France [22] Filed: May 25, 1970 [21] Appl. No.: 40,278

[30] Foreign Application Priority Data May 30, 1969 France 17791 [52] U.S. Cl ..260/681, 252/437, 252/432, 260/348.5 R, 260/484 A, 260/497 R, 260/610 B, 260/632 C, 260/635 H, 260/669 QZ, 260/682 [51] Int. Cl ..C07c 1/00, C07c 1/20 [58] Field of Search ..260/681 [56] References Cited UNITED STATES PATENTS 3,391,214 7/1968 Fetterly ..260/681 3,403,193 9/1968 Russell... ...260/669 3,350,422 10/1967 Kollar ..260/348 5 2,776,301 l/l957 Payne et al... 260/635 H X 3,238,264 3/1966 Rowton ..260/632 3,391,213 7/1968 Fetterly ..260/681 [45] May 23, 1972 FOREIGN PATENTS OR APPLICATIONS 577,364 5/1964 Great Britain ..260/681 935,631 9/1963 Great Britain.... ....260/68l 1,274,507 9/1961 France ..260/681 Primary Examiner-Delbert E. Gantz Assistant ExaminerG. E. Schmitkons Attorney-Curtis, Morris & Safford [57] ABSTRACT A method of preparing a diolefin and an olefin or an alkenyl benzene hydrocarbon simultaneously from more highly saturated hydrocarbons, said latter respectively having the same carbon structure as the desired end product pair, wherein the more highly saturated hydrocarbon precursors are reacted with oxygen to form respective hydroperoxides, the latter are reacted with an ethylenic hydrocarbon having the same carbon structure as the diolefin precursor to form an epoxide or glycol which are in turn dehydrated to the desired diolefin; the first hydroperoxide forms an alcohol which is dehydrated to reform the ethylenic hydrocarbon for recycling; the second hydroperoxide forms an alcohol which is dehydrated to the desired olefin or alkenylbenzene (depending upon the form of the precursor); and the ketone byproducts formed during the reaction of said hydroperoxides with said ethylenic hydrocarbon (these being the other principle byproducts in this process) are reduced to an alcohol and then dehydrated to said ethylenic hydrocarbon for recycling.

The foregoing process is particularly advantageous in the simultaneous production of isoprene and isobutylene from isopentane and isobutane or of isoprene and styrene from isopentane and ethyl benzene.

11 Claims, 2 Drawing Figures Patented May 23, 1972 2 Sheets-Sheet 1 METHOD FOR THE SIMULTANEOUS PREPARATION OF A DIOLEFIN AND AN OLEFIN The present invention relates to a method for producing a diolefin and an olefin simultaneously from more highly saturated compounds.

It has particular commercial application in the simultaneous preparation of isoprene and another olefin, such as isobutylene or styrene.

It is known that these compounds are important raw materials useful in numerous synthesis processes and particularly for the production of various polymers, such as in the preparation of synthetic rubber.

As isoprene is of prime importance for the manufacture of synthetic rubber, various processes have already been proposed for its production.

One of these processes consists in hydroperoxidizing isopentane with oxygen and reacting the resultant hydroperoxide with 2-methyl-2-butylene to form methyl 2,3- epoxy butane. The latter is then isomerized to form alcohol, which is finally dehydrated to isoprene. isomerization and dehydration are usually combined in a single operation with the use of a suitable catalyst. This method has the drawback of giving a poor yield of isoprene as compared with the quantity of isopentane used because of the formation of various byproducts. On the one hand, the isomerization-dehydration operation is accompanied by an isomerization into compounds with carbonyl function (formation of methyl isopropylketone) and even of a structural isomerization (formation of trimethyl acetaldehyde); on the other hand, both during the isopentane oxidation phase and during the following operations, other byproducts are formed, particularly tertiary amyl alcohol and methyl isopropyl ketone. Since not all of these products can be converted further into isoprene and since the different phases of the process are of poor selectivity, one therefore obtains only a poor conversion of the isopentane into isoprene.

It has also been proposed to prepare isoprene and styrene simultaneously from methyl butylene and ethyl benzene. Ethyl benzene is hydroperoxidized with oxygen. The resultant hydroperoxide itself serves as an oxidizing agent for the 2- methyl-Z-butylene to form an epoxide and an alcohol. By dehydration, this alcohol gives styrene while, as previously, the epoxide is isomerized to alcohol. This latter alcohol is dehydrated to isoprene.

This process has the same drawbacks as the preceding process.

One object of the present invention is to improve the profitability of the processes for the production of isoprene or other diolefin by utilizing the byproducts of the intermediate reactions.

Another object of the invention is to propose a method for the simultaneous preparation of an olefin or an alkenyl benzene hydrocarbon.

In the following description and the claims, the following expressions will have the following meanings:

or alpha glycols: diols, the two hydroxyl functions of which are attached to two adjacent carbon atoms of the molecule.

a alpha epoxides: olefin oxides, the oxygen atom of which is bound to two adjacent carbon atoms.

The method of the present invention comprises separately contacting with molecular oxygen under peroxidation conditions 21 first hydrocarbon, for example a branched saturated hydrocarbon, having the same carbon structure as the diolefin which it is desired to prepare and a second hydrocarbon, for example a branched saturated hydrocarbon or alkylbenzene hydrocarbon having the same carbon structure as the olefin or alkenylbenzene, desired, so as to produce a first and a second hydroperoxide respectively; reacting the said first and second hydroperoxides with the same ethylenic hydrocarbon having the same carbon structure as the first hydrocarbon in the presence of a suitable catalyst so as to obtain from said ethylenic hydrocarbon an alpha epoxide or an alpha glycol of the same carbon structure as the first hydrocarbon; said alpha epoxide or alpha glycol is then converted by dehydration to the corresponding diolefin; (with the alpha epoxide first being separately, or simultaneously, isomerized) the first hydroperoxide furthermore leading to the formation of a first alcohol of the same carbon structure as the said first hydrocarbon, which first alcohol is dehydrated to reform the said ethylenic hydrocarbon, which is recycled to the treatment of the said first and second hydroperoxides; the second hydroperoxide furthermore leading to the formation of a second alcohol of the same carbon structure as the said second hydrocarbon, which second alcohol is dehydrated to form the desired olefin or alkenylbenzene; the ketone byproducts (formed by isomerization during the reaction of the said first and second hydroperoxides with the said ethylenic hydrocarbon and during the dehydration of the said alpha epoxide or the said alpha glycol) being convened. in known manner, by reduction into an alcohol and then dehydrated to the said ethylenic hydrocarbon for recycling.

As the two types of hydroperoxides react with the same ethylenic hydrocarbon, it is possible to effect the oxidation operations of this hydrocarbon either in separate enclosures or in the same enclosure, these two variants naturally both falling within the scope of the invention and the choice between them depending only on the difficulties of separating the resultant products for the further phases of the process.

The process in accordance with the present invention therefore has the great advantage over the conventional processes directed at the simultaneous preparation of a diolefin and an olefin or an alkenylbenzene of avoiding discarding large quantities of byproducts thereby adversely affecting the economy of such processes. In contrast, in the present invention, the ketones formed are converted into an intermediate product which is used in the very process of production of the diolefin and olefin or alkenylbenzene; namely the ethylenic hydrocarbon, which is thus recycled in full (except for leakage).

The process in accordance with the present invention can be applied in principle to the production of any olefin/diolefin or alkenylbenzene/diolefin pairing. However, due to insufficient yields in the phase of preparation of the hydroperoxidizing of saturated hydrocarbons having three or less carbon atoms, the invention is more particularly useful in the preparation of diolefins derived from a preferably branched condensation hydrocarbon having four or more carbon atoms. The olefin or alkenylbenzene can be obtained either from paraffins, for instance isobutane or from alkyl aromatic hydrocarbons such as ethyl benzene, cumene, etc. or from any hydrocarbon which can give a hydroperoxide.

The conversion of the ketone into the corresponding ethylenic hydrocarbon can be effected by any known method for the hydrogenation of a ketone to the corresponding alcohol and the dehydration of said alcohol.

Likewise, the reaction of the hydroperoxides with ethylenic hydrocarbon in order to obtain an alpha-glycol or an alphaepoxide can be carried out in accordance with any known process; for example, alpha-glycol can be obtained in the presence of water by the process described by the applicant in its U.S. application, Ser. No. 866,357 filed Oct. 14, 1969 based upon its priority French Pat. application, Ser. No. PV 169,862 filed on Oct. 14, 1968. The diol obtained in this manner can also be dehydrated in known fashion, particularly in the presence of lithium phosphate prepared under acid conditions atomic Li/P ratio of less than three in the reaction medium for the preparation of the catalystby the process described by the applicant in its U.S. application, Ser. No. 30,276 filed Apr. 20, 1970 based upon its priority French Pat. application filed on Apr. 22, 1969 under National Registration No. 69/12684.

Likewise, alpha-epoxide or alpha glycol can also be converted into the corresponding diolefin by any known means, and particularly by preparing the monoacetate corresponding to the glycol and pyrolyzing said monoacetate to olefinic alcohol, which can then easily be dehydrated by the process described by the applicant in its US. application, Ser. No. 34,172 filed May 4, 1970 based upon its priority French Pat. application filed on May 8, 1969 under National Registration No. 69/14751.

1n the specification and in the accompanying drawings there are described and shown two illustrative embodiments of the invention and various modifications thereof are suggested, but it is to be understood that these are not intended to be exhaustive, but on the contrary, are given for purposes of illustration in order that others skilled in the art may more fully understand the invention so that they may modify and adapt it in various forms, each as may be best suited to the conditions of a particular use.

The various objects, aspects, and advantages of the present invention will be more fully understood from a consideration of the following specification in conjunction with the accompanying drawings in which:

FIG. 1 illustrates the simultaneous preparation of isoprene and isobutylene from isopentane and isobutane;

FIG. 2 refers to the simultaneous production of isoprene and styrene from isopentane and ethyl benzene.

Referring, first of all, to FIG. 1:

lsopentane and air are introduced by the lines 1 and 2 respectively into a reactor 3 where they are heated. to a temperature of about 150 C to form the corresponding hydroperoxide. The latter is transferred via a line 4 with the excess isopentane, to a film evaporator 5 from which the hydroperoxide is evacuated through a line 6 while the excess isopentane is recycled through the line 7 to the feed of the reactor 3.

ln similar fashion, the lines 8 and 9 feed a reactor 10 at a temperature of 140 with isobutane and air respectively, line 11 evacuating the resultant hydroperoxide and the excess isobutane from said reactor towards a film evaporator 12. The hydroperoxide which has been separated out is evacuated by a line 13 which joins the line 6 while the excess isobutane is recycled via a line 14 to the feed of the reactor 10.

The epoxidation/hydration reactor 15 is fed via the line 6 on the one hand and on the other hand via lines 16 and 17 which conduct water and a mixture of 2-methyl-2-butylene and catalyst respectively. The catalyst consists for instance of molybdenum napthenate, it being understood that the use of other catalysts falls within the scope of the invention.

The temperature of the reactor is about 120 C and the dwell time of the products introduced is about 1 hour, during which time the conversion of the hydroperoxides is practically complete.

A line 18 evacuates the products emerging from the reactor 15 towards the distillation column 19; at the top of said column the 2-methyl-2-butylene which has not undergone epoxidation/hydration in the reactor 15 is evacuated via a line 20; the line 20 connects up with the line 17. The line 21 collects the other products formed in 15 and introduces them into a distillation column 22. At the bottom of the column, a mixture of methyl 2,3-butanediol and epoxidation/hydration catalyst is collected by the line 23. The catalyst is eliminated by passage through the filter 24. The methyl 2,3-butanediol is introduced through the line 25 into a reactor 26 where it passes at 500 C over lithium phosphate, Li PO which has been prepared in accordance with the method described in the aforementioned French Pat. application filed on Apr. 22, 1969.

The products emerging from the reactor 26 via the line 27 are separated in a distillation column 28 at the top of which at 29 isoprene emerges and at the bottom of which small quantities primarily of methyl isopropylketone are collected by the line 30.

At the top of the distillation column 22, a mixture composed primarily of methyl isopropyl ketone, tertiary butyl alcohol and 2-methyl Z-butanol is collected by the line 31. The line 31 connects up with the line via the line 32, hydrogen is fed; and the mixture from these three lines is introduced via the line 33 into a hydrogenation reactor 34 containing nickel on pumice stone support; the pressure is 50 kg/cm2, the temperature 250 C, and the time of contact 1 hour. At the outlet, there is collected through the line 35 a mixture of 2-methyl 3- butanol, 2-methyl 2-butanol and tertiary butanol, which is introduced into a dehydration reactor 36 containing thorium oxide at a temperature of 400 C; at the outlet, a mixture of isobutylene, 2-methyl Z-butylene and water is collected by the line 37; the water is removed at the bottom of the distillation column 38 via the line 39; at the top of this column, the mixture of olefins passes through the line 40 and is separated in a distillation column 41. The isobutylene passes off at the top via the line 42 and the 2-methyl 2-butylene recovered by the line 43 is recycled, connecting up with line 20 to form the line 17.

A second embodiment of the invention is illustrated in FIG. 2.

ln this embodiment, a reactor 44 which is heated to 150 C is fed with isopentane and air through the lines 45 and 46 respectively. The mixture of hydroperoxide formed and of excess isopentane is discharged through a line 47 into a flash distillation column 48 at the bottom of which the hydroperoxide is collected by the line 49, while at the top the excess isopentane is recovered and recycled via the line 50 to the feed of the reactor 44.

In similar manner, a reactor 51, heated to a temperature of 140 C, is fed via the lines 52 and 53 respectively with ethyl benzene and air, the outgoing mixture being evacuated by a line 54 to a flash distillation tower 55 at the base of which the hydroperoxide is collected which is then evacuated through a line 56 which connects up with the line 49 while at the top the excess ethyl benzene is collected and recycled by the line 57 to the feed of the reactor 5 l.

The line 49 feeds an epoxidation reactor 58 at a temperature of 120 C, also fed with 2-methyl 2-butylene and with an epoxidation catalyst, for instance one having a base of molybdenum, via a line 59. The mixture emerging at 60 from this reactor 58 is separated in a distillation column 61 at the top of which via 62 the excess Z-methyl Z-butylene is collected and recycled to the feed of the reactor 58 while at the bottom of the column 61 a mixture of methyl 2,3-epoxy butane, methyl benzyl alcohol, tertiary amyl alcohol and methyl isopropyl ketone is recovered at 63. This mixture is itself separated in a column 64 at the top of which the epoxide is collected in the line 65.

The methyl 2,3-epoxy butane is mixed in the reactor 66 with a slight excess of acetic acid introduced through the line 67 so as to form a monoacetate in the presence of a suitable catalyst, for instance ferric chloride, also introduced through the line 67, as described in the aforementioned French Patent application filed on May 8, 1969.

The resultant mixture is transferred via the line 68 to a pyrolysis reactor 69. The efflux evacuated through the line 70 is diluted with water arriving at 71 and introduced via a line 72 into a distillation column 73. In the latter, azeotropic distillation makes it possible to recover acetic acid at the bottom of the tower. The acetic acid is recycled via 67, while the olefin alcohols are collected from the top of the column at 74.

These alcohols are catalytically dehydrated over thorium oxide at 400 C in the reactor 75. The efflux is transferred via the line 76 into an enclosure 77 where a light phase consisting essentially of isoprene is separated by settling and collected at 78. The pure isoprene is separated from this phase by distillation in a column 80. The isoprene passes off from the top of the column through the line 81. The other components are introduced via the line 82 into a distillation column 83 at the top of which themethyl isopropyl ketone passes over via 84. The olefin alcohols which have not been dehydrated are located at the bottom of the column and are recycled via the line 85 into the reactor 75.

The heavy phase separated at 79 contains unconverted olefin alcohols primarily 2-methyl 3-butylene 2-ol. These alcohols are recycled via the line 86 into the reactor after possible distillation in a column 87; the distillation residue being eliminated at 88.

At the bottom of the distillation column 64, there is collected a mixture composed primarily of methyl benzyl alcohol, 2-methyl 2-butanol, methyl isopropyl ketone and the epoxidation catalyst; the line 89 introduces this mixture into a filter 90 which retains the catalyst.

The mixture emerges at 91; the line 84 connects up with the line 91; thus all the methyl isopropyl ketone formed is recycled; after injection of hydrogen in 92, the mixture enters a hydrogenation reactor 93 containing a catalyst formed of nickel on pumice stone. The pressure is 50 kg/cm2, the temperature 250 C and the time of contact 1 hour. At the outlet, the reduction products are collected by the line 94 and introduced into a catalytic dehydration reactor 95 formed of thorium oxide brought to 400 C. The mixture is introduced via the line 96 into a distillation column 97. At the top of the column 97, the 2-methyl 2-butylene passes off and is recycled via the line 98 to the epoxidation reactor 58; the styrene is extracted via line 99.

The invention is further illustrated by the following examples.

EXAMPLE I The simultaneous preparation of isoprene and isobutylene is effected from isopentane and isobutane in the manner illustrated in FIG. 1.

1,000 parts by weight of isopentane and 776 parts by weight of isobutane were employed. For 100 mols of isopentane used there are obtained 82.0 mols of isoprene and 90.0 mols of isobutylene which corresponds to 775 parts by weight of isoprene and 700 parts by weight of isobutylene, without any ketone byproduct remaining due to the recyclings effected. The yield by weight of isobutylene with respect to isobutane is: 90.2, which is (700/776)-(58. 12/56. 93.4% oftheory.

EXAMPLE II The simultaneous preparation of isoprene and styrene is effected from isopentane and ethyl benzene as illustrated in FIG. 2.

1,000 parts by weight of isopentane and 913 parts by weight of ethyl benzene are used. For 100 mols of isopentane used, there are obtained 84.8 mols of isoprene and 46.5 mols of styrene, which corresponds to 799 parts by weight of isoprene and 672 parts by weight of styrene, without any ketone byproduct remaining due to the recyclings effected. The yield of styrene by weight with respect to ethylbenzene is: 73.6, which is (672/913)'( 106.16/104. 14) 75.1% oftheory.

We claim:

1. A method for simultaneously preparing a diolefin and an olefin or an alkenyl benzene hydrocarbon comprising separately contacting with molecular oxygen under peroxidation conditions a first saturated hydrocarbon having the same carbon structure as the diolefin end product and a second saturated hydrocarbon or alkyl benzene hydrocarbon having the same carbon structure as the desired olefin or alkenyl benzene end product to produce a first and a second hydroperoxide respectively; reacting both the said first and second hydroperoxides with an ethylenic hydrocarbon having the same carbon structure as the said first hydrocarbon in the presence of a suitable catalyst to obtain from said ethylenic hydrocarbon an alpha-epoxide or an alpha glycol of the same carbon structure as the first hydrocarbon; converting the alpha epoxide by an isomerization-dehydration process to the diolefin end product; or dehydrating the alpha-glycol into the corresponding diolefin end product; the first hydroperoxide in the reaction with said ethylenic hydrocarbon yields a first alcohol of the same carbon structure as the said first hydrocarbon; dehydrating said first alcohol to give said ethylenic hydrocarbon which is recycled to the treatment of the said first and second hydroperoxides; the second hydroperoxide in the reaction with said ethylenic hydrocarbon yields a second alcohol of the same carbon structure as the said second hydrocarbon; dehydrating said second alcohol to give the desired olefin or alkenyl benzene end product; the ketone by products formed by isomerlzation during the reaction of the said first and second hydroperoxides with the said ethylenic hydrocarbon and during the isomerization-dehydration of the said alpha-epoxyde or during the dehydration of the said alpha-glycol being converted by reduction to an alcohol and then dehydrated to said ethylenic hydrocarbon and recycled.

2. A method according to claim 1 wherein the said first and second hydrocarbons are branched.

3. A method according to claim 2 wherein oxidation of the ethylene hydrocarbon by the first and second hydroperoxides is carried out in separate enclosures.

4. A method according to claim 2, wherein the oxidation of the ethylene hydrocarbon by the first and the second hydroperoxides is carried out simultaneously in the same enclosure.

5. A method according to claim 2 wherein the oxidation of the ethylene hydrocarbon by the hydroperoxides for the obtaining of an alpha-glycol is effected in the presence of water.

6. A method according to claim 2 in which the alpha-glycol is dehydrated in the presence of a catalyst comprising lithium phosphate prepared in a reaction medium containing a stoichiometric excess of phosphoric acid.

7. A method according to claim 2 wherein the alpha-epoxide is converted to a monoester which is then pyrolized to an olefin alcohol, the latter being then dehydrated to the corresponding diolefin.

8. A method according to claim 2 wherein said first and second hydrocarbons are respectively isopentane and isobutane and the end products yielded are isoprene and isobutylene.

9. A method according to claim 2 wherein said first and second hydrocarbons are respectively isopentane and ethyl benzene and the end products yielded are isoprene and styrene.

10. A method according to claim 2 wherein the first hydrocarbon has four or more carbon atoms.

11. A method according to claim 2, wherein the expoxidation/hydration reactions proceed simultaneously with a suitable catalyst to yield directly the alpha glycol. 

2. A method according to claim 1 wherein the said first and second hydrocarbons are branched.
 3. A method according to claim 2 wherein oxidation of the ethylene hydrocarbon by the first and second hydroperoxides is carried out in separate enclosures.
 4. A method according to claim 2, wherein the oxidation of the ethylene hydrocarbon by the first and the second hydroperoxides is carried out simultaneously in the same enclosure.
 5. A method according to claim 2 wherein the oxidation of the ethylene hydrocarbon by the hydroperoxides for the obtaining of an alpha-glycol is effected in the presence of water.
 6. A method according to claim 2 in which the alpha-glycol is dehydrated in the presence of a catalyst comprising lithium phosphate prepared in a reaction medium containing a stoichiometric excess of phosphoric acid.
 7. A method according to claim 2 wherein the alpha-epoxide is converted to a monoester which is then pyrolized to an olefin alcohol, the latter being then dehydrated to the corresponding diolefin.
 8. A method according to claim 2 wherein said first and second hydrocarbons are respectively isopentane and isobutane and the end products yielded are isoprene and isobutylene.
 9. A method according to claim 2 wherein said first and second hydrocarbons are respectively isopentane and ethyl benzene and the end products yielded are isoprene and styrene.
 10. A method according to claim 2 wherein the first hydrocarbon has four or more carbon atoms.
 11. A method according to claim 2, wherein the expoxidation/hydration reactions proceed simultaneously with a suitable catalyst to yield directly the alpha glycol. 